Multiple core transformer assembly

ABSTRACT

A circuit interrupting device includes a grounded neutral transformer core, a high frequency transformer core, and a differential transformer core nested within the grounded neutral transformer core and/or the high frequency transformer core. The grounded neutral transformer core and the high frequency transformer core are disposed in a stacked configuration with one another.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 15/287,837, filed on Oct. 7, 2016, the entirecontents of which are incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates to fault circuit interrupters and, moreparticularly, but not exclusively, to combined arc fault and groundfault circuit interrupters.

Related Art

Electrical devices such as fault circuit interrupters are typicallyinstalled into a wall box/electrical box and are typically installedwithin/on a wall. Typically, the depth of the wall box is constrained bythe depth of the wall and/or the depth of the wall's framing members.Electrical wiring is typically fed into a region of the wall box forelectrical connections to/from the electrical device(s) resulting in aportion of the wall box's volume/depth being utilized by this wiring,while the remaining volume/depth of the wall box is utilized by aninstalled electrical device. Wall boxes are typically configured toreceive two electrical connections, one for line and the other for load,each containing a phase wire, a neutral wire and a ground wire, for atotal of five or even six wires being fed/connected into the wall box.Since normal installation of electrical devices is typically constrainedby the distance in which they may extend beyond the finished wallsurface, the greater the depth of the housing of the electrical device,the harder it is to fit an electrical device within the constraintsposed by the electrical wall box and the finished wall surface.

In many cases, circuit interrupters are incorporated into single gangelectrical devices such as duplex receptacles, a switch or combinationswitch receptacles. Single gang electrical enclosures, such as a singlegang wall boxes, are standardized in the electrical industry via NEMAStandard OS-1. For example, a single-gang wall box has a nominal heightof about 3 inches and a nominal width of about 2 inches.

Due to the space restraints, and because of the complexity of electricaldesigns of fault circuit interrupter designs in general (i.e., circuitinterrupters typically include a number of electrical components),circuit interrupter designs based upon the present state of the art arechallenged for reduction in the depth of the device.

SUMMARY

The following presents a summary of the claimed subject matter in orderto provide a basic understanding of some aspects of the claimed subjectmatter. This summary is not an extensive overview of the claimed subjectmatter. It is intended to neither identify key or critical elements ofthe claimed subject matter nor delineate the scope of the claimedsubject matter. Its sole purpose is to present some concepts of theclaimed subject matter in a simplified form as a prelude to the moredetailed description that is presented later.

In an aspect of the present disclosure, a circuit interrupting device isprovided and includes a grounded neutral transformer core, a highfrequency transformer core, and a differential transformer core. Thegrounded neutral transformer core and the high frequency transformercore disposed in a stacked configuration with one another. Thedifferential transformer core is nested within the grounded neutraltransformer core and/or the high frequency transformer core.

In some embodiments, the differential transformer core may extend alongan entire height of the grounded neutral transformer core and an entireheight of the high frequency transformer core.

It is contemplated that the differential transformer core may extendalong an entire height of the grounded neutral transformer core and onlypartially along a height of the high frequency transformer core.

It is envisioned that the differential transformer core may extend alongan entire height of the high frequency transformer core and onlypartially along a height of the grounded neutral transformer core.

In some embodiments, the grounded neutral transformer core, the highfrequency transformer core, and/or the differential transformer core mayhave a substantially rectangular cross-section.

It is contemplated that the grounded neutral transformer core and thehigh frequency transformer core may cooperatively define a cavitytherein and that the differential transformer core received within thecavity. The differential transformer core may extend through an entireheight of the cavity.

It is envisioned that each of the grounded neutral transformer core andthe high frequency transformer core may include a top surface and abottom surface. The bottom surface of the grounded neutral transformercore or the bottom surface of the high frequency transformer core may besupported on the top surface of the other of the grounded neutraltransformer core or the high frequency transformer core.

In some embodiments, the grounded neutral transformer core and the highfrequency transformer core may be coaxial with one another.

It is contemplated that the differential transformer core may bedisposed concentrically within the grounded neutral transformer coreand/or the high frequency transformer core.

It is envisioned that each of the grounded neutral transformer core andthe high frequency transformer core may define an inner chamber thereinand that the differential transformer core may be disposed within theinner chamber of the grounded neutral transformer core and/or the innerchamber of the high frequency transformer core.

In some embodiments, the circuit interrupting device may further includea magnetic shield associated with the differential transformer core. Themagnetic shield may be disposed below the differential transformer core.

In another aspect of the present disclosure, a method of manufacturing acircuit interrupting device is provided. The method includes stacking agrounded neutral transformer core and a high frequency transformer coreand nesting a differential transformer core within a central cavitycooperatively defined by the stacked grounded neutral transformer coreand the high frequency transformer core.

In some embodiments, stacking the grounded neutral transformer core andthe high frequency transformer core may include positioning the groundedneutral transformer core on the high frequency transformer core orpositioning the high frequency transformer core on the grounded neutraltransformer core.

It is contemplated that nesting the differential transformer core withinthe central cavity may include disposing the differential transformercore concentrically within the grounded neutral transformer core and/orthe high frequency transformer core.

It is envisioned that the method may further include positioning thedifferential transformer core on a magnetic shield.

In yet another aspect of the present disclosure, a circuit interruptingdevice is provided that includes a grounded neutral transformer core, ahigh frequency transformer core in abutting engagement with the groundedneutral transformer core, and a differential transformer coreconcentrically disposed within the grounded neutral transformer coreand/or the high frequency transformer core.

In some embodiments, the grounded neutral transformer core and the highfrequency transformer core may be coaxial with one another.

It is contemplated that the grounded neutral transformer core or thehigh frequency transformer core may be disposed on top of the other ofthe grounded neutral transformer core or the high frequency transformercore.

Further scope of applicability of the present disclosure will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the presentdisclosure, are given by way of illustration only, since various changesand modifications within the spirit and scope of the present disclosurewill become apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more aspects of the present invention are particularly pointedout and distinctly claimed as examples in the claims at the conclusionof the specification. The foregoing and other objects, features, andadvantages of the present invention may be more readily understood byone skilled in the art with reference being had to the followingdetailed description of several embodiments thereof, taken inconjunction with the accompanying drawings wherein like elements aredesignated by identical reference numerals throughout the several views,and in which:

FIGS. 1A-1C collectively illustrate a schematic diagram of a combinedarc fault circuit interrupter (AFCI)/ground fault circuit interrupter(GFCI) in accordance with the principles of the disclosure;

FIG. 2 is a perspective view of the combined AFCl/GFCI printed circuitboard assembly;

FIG. 3 is a top view of a three core transformer assembly;

FIG. 4 is a side view of the three core transformer assembly of FIG. 3;

FIG. 5 is a cross-sectional view of the three core assembly of FIG. 3;

FIG. 6 is a cross-sectional view of another configuration of the threecore assembly of FIG. 3;

FIG. 7 is a cross-sectional view of yet another configuration of thethree core assembly of FIG. 3;

FIG. 8 is a cross-sectional view of yet another configuration of thethree core assembly of FIGS. 3; and

FIG. 9 is a perspective view of the three core transformer assembly ofFIG. 3 according to the disclosure.

The figures depict embodiments of the present disclosure for purposes ofillustration only. One skilled in the art will readily recognize fromthe following discussion that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles of the present disclosure described herein.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings. However, it isto be understood that the disclosed embodiments are merely exemplary ofthe disclosure and may be embodied in various forms. Well-knownfunctions or constructions are not described in detail to avoidobscuring the present disclosure in unnecessary detail. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a basis for the claims and asa representative basis for teaching one skilled in the art to variouslyemploy the present disclosure in virtually any appropriately detailedstructure.

For the purposes of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the exemplaryembodiments illustrated in the drawings, and specific language will beused to describe the same. It will nevertheless be understood that nolimitation of the scope of the present disclosure is thereby intended.Any alterations and further modifications of the inventive featuresillustrated herein, and any additional applications of the principles ofthe present disclosure as illustrated herein, which would occur to oneskilled in the relevant art and having possession of this disclosure,are to be considered within the scope of the present disclosure.

The present disclosure is directed to fault circuit interrupters and, inparticular, a combined AFCl/GFCI device. Among other components, theAFCI portion may include, or be used with a high frequency sensor, acurrent sensor, and a differential sensor. Generally the current sensorand the differential sensor operate at low frequencies, typically lowerthan the high frequency sensor. Any one of the three sensors can each becommunicatively arranged and configured to measure electricalcharacteristics of a line or device conductive path such as a phaseconductive path or a neutral conductive path. Some of thesecharacteristics can include high frequency signals, current, and currentdifferential on the device current path including one or more of thephase conductive paths and the neutral conductive paths. The sensors maybe communicatively arranged and configured such that the positioning ofany one of the sensors enables the sensor to read/sense thecorresponding electrical parameter(s) associated with any one of, or anypair of conductors, including pairings which are arranged to readdifferential signals as well as additive signals. Sensor arrangementand/or positioning can include, but not be limited to: adjacent to thedevice conductive path, electrically coupled to the device conductivepath, magnetically coupled to the device conductive path, positionedsuch that the device conductive path passes through a core of the sensorand/or any combination of the foregoing either in differential oradditive arrangements.

For example, the high frequency sensor may be configured to measure highfrequency signals, particularly high frequency noise. The current sensormay be configured to measure a current value. The differential sensormay be configured to measure a current differential between, e.g., thephase and neutral conductive paths. The output from the sensors areconnected to an analog signal processor circuit that can comprise anysuitable circuit elements known in the art such as but not limited toamplifiers, rectifiers, comparators (or a combination thereof), or otherelements to condition the signal from one or more of sensors beforebeing input into processor. Alternatively, one or more of the outputsignals from the sensors may be provided directly to the processorwithout any analog conditioning.

The processor can be any suitable type of processor such as amicroprocessor, microcontroller, ASIC, FPGA, or the like. It should alsobe noted that the term “processor” can be used interchangeably withmicroprocessor, microcontroller, ASIC, FPGA, or the like. The processoris configured/programmed to analyze output signals provided by one ormore of the sensors and determine if one or more predetermined conditionexists; e.g., an arc fault, ground fault, or the like. If the processordetects a predetermined condition, the processor may beconfigured/programmed to trigger an interrupting mechanism to interruptpower to one or more of the phase and neutral conductive paths, thusdisconnecting power to the load.

The GFCI portion of the device includes a grounded neutral (GN)transformer as well as the differential sensor of the AFCI portion andthe GN transformer is utilized in sensing or monitoring for groundedneutral faults. By way of example, a GN transformer typically includes acore having hot and neutral lines extending therethrough, which forms afirst winding, with a second winding wound on the core. If a groundedneutral fault occurs, the differential sensor and the GN transformercreate positive feedback causing circuitry to oscillate. When thishappens, the circuitry senses this as a high frequency ground fault andthe device trips. A more detailed description of an exemplary GNtransformer may be found, for example, in U.S. Pat. No. 6,538,863, theentire contents of which are incorporated by reference herein. Thedifferential sensor may or may not be conditioned by an analog signalprocessor circuit as described above before being provided to theprocessor to determine if a dangerous condition exists.

In the embodiments described herein, a combined AFCl/GFCI requires four(4) different sensors or transformer cores to detect one or morepredetermined conditions. Because of the four different transformercores, packaging/layout of the device's electrical, mechanical andelectro-mechanical components, as well as routing of the variousconductive/current paths so that the AFCl/GFCI iselectrically/electro-mechanically operable, physically manufacturableand suitably sized for installation in standard wall boxes becomeschallenging. The embodiments described herein arrange/package three ofthe four sensors/transformer cores in the same physical volume that twotransformer cores might otherwise occupy in conventional devices.

Turning to FIGS. 1 and 2, a combined AFCl/GFCI is shown generally as 10.Although FIGS. 1A-1C depict a specific wiring scheme layout, the presentdisclosure is not limited to such a layout. As shown in FIGS. 1A-1C,AFCl/GFCI 10 has a three core assembly 12 that includes a GN transformercore 14, a differential transformer core 16, and a high frequencytransformer core 18, such as, for example, a Rogowski core. In someembodiments, assembly 12 may include a fourth transformer core 22 (FIGS.1A-1C). FIG. 2 depicts the AFCl/GFCI 10 in its printed circuit board(PCB) assembly configuration 20. The dimensions of PCB assembly 20permit PCB assembly 20 to be assembled within a single gang devicehousing for mounting in a standard wall box. The three core assembly 12,which will be discussed in more detail below with reference to theembodiment depicted FIGS. 3-5, is arranged on one side of, and at oneend of, the PCB assembly 20, such that the total volume occupied withinthe device housing is minimized.

In order to minimize the size of the three core assembly 12, thedifferential transformer core 16 is nested within the GN transformercore 14 and the high frequency transformer core 18, while the GNtransformer core 14 and the high frequency transformer core 18 arearranged in a stacked configuration. In particular, the GN transformercore 14 generally has a top surface 14 a, a bottom surface 14 b, anouter circumferential surface 14 c, and an inner circumferential surface14 d that defines a central cavity/volume 17 a. The high frequencytransformer core 18 also generally has a top surface 18 a, a bottomsurface 18 b, an outer circumferential surface 18 c, and an innercircumferential surface 18 d that defines a central cavity/volume 17 b.As such, each of the GN transformer core 14 and the high frequencytransformer core 18 assumes a generally toroidal shape having agenerally rectangular transverse cross-section. It is contemplated thatall or some of the above-noted surfaces of the GN transformer core 14and the high frequency transformer core 18 may be flat or arcuate.

The stacked configuration results in one or the other of the GNtransformer core 14 and the high frequency transformer core 18 beingdisposed on, or seated on top of, the other such that the bottom surface14 b or 18 b of one transformer core 14 or 18 is in proximalrelation/abutting engagement with the top surface 14 a or 18 a of theother transformer core 14 or 18. In either stacked configuration (i.e.,the GN transformer core 14 above/atop the high frequency transformercore 18 or the high frequency transformer core 18 above/atop the GNtransformer core 14), the central cavity/volume 17 a of GN transformercore 14 and the central cavity/volume 17 b of the high frequencytransformer core 18 cooperatively define one continuous central bore 17of the stacked GN transformer core 14 and the high frequency transformercore 18. The central bore 17 of the stacked GN transformer core 14 andthe high frequency transformer core 18 is dimensioned for receipt of thedifferential transformer core 16, as will be described in detail below.

Turning to FIGS. 3-8, three core assembly 12 has an axis A that runsthrough the center of the central bore 17 of the stacked GN transformercore 14 and the high frequency transformer core 18. In one embodimentwhere the differential transformer core 16 is concentrically disposedwithin the central bore 17 of the stacked GN transformer core 14 and thehigh frequency transformer core 18, the centers of the GN transformercore 14, differential transformer core 16, and high frequencytransformer core 18 are all arranged along axis A (i.e., the GNtransformer core 14 and the high frequency transformer core 18 arecoaxial with one another, and the differential transformer core 16 isconcentrically disposed within the GN transformer core 14 and the highfrequency transformer core 18).

As described briefly above, the GN transformer core 14 defines an innerchamber or central cavity/volume 17 a and the high frequency transformercore 18 defines an inner chamber or central cavity/volume 17 b. Thedifferential transformer core 16 is disposed or nested within both theinner chamber 17 a of the GN transformer core 14 and the inner chamber17 b of the high frequency transformer core 18. In another embodiment,the differential transformer core 16 is disposed or nested within onlythe inner chamber 17 a of the GN transformer core 14. In yet anotherembodiment, the differential transformer core 16 is disposed or nestedwithin only the high frequency transformer core 18.

The differential transformer core 16 has a height H_(D), the GNtransformer 14 has a height H_(N), and the high frequency transformercore 18 has a height H_(R). In one embodiment, as shown in FIG. 5, theheight H_(D) of the differential transformer core 16 may be less thanthe combined heights H_(N) and H_(R) of the GN transformer core 14 andthe high frequency transformer core 18 so that the top surface 16 a ofthe differential transformer core 16 is coplanar with the top surface 14a of the GN transformer core 14 while the bottom surface 16 b of thedifferential transformer core 16 is recessed from the bottom surface 18b of the high frequency transformer core 18. In another embodiment, asshown in FIG. 6, the height H_(D) of the differential transformer core16 may be less than the combined heights H_(N) and H_(R) of the GNtransformer core 14 and the high frequency transformer core 18 so thatthe top surface 16 a of the differential transformer core 16 is recessedfrom the top surface 14 a of the GN transformer core 14 while the bottomsurface 16 b of the differential transformer core 16 is coplanar withthe bottom surface 18 b of the high frequency transformer core 18. Inyet another embodiment, as shown in FIG. 7, the height H_(D) of thedifferential transformer core 16 may be less than the combined heightsH_(N) and H_(R) of the GN transformer core 14 and the high frequencytransformer core 18 so that the top surface 16 a of the differentialtransformer core 16 is recessed from the top surface 14 a of the GNtransformer core 14 and the bottom surface 16 b of the differentialtransformer core 16 is recessed from the bottom surface 18 b of the highfrequency transformer core 18. In another embodiment still, as shown inFIG. 8, the height H_(D) of the differential transformer core 16 may beequal to the combined heights H_(N) and H_(R) of the GN transformer core14 and the high frequency transformer core 18 so that the top surface 16a of the differential transformer core 16 is coplanar with the topsurface 14 a of the GN transformer core 14 and the bottom surface 16 bof the differential transformer core 16 is coplanar with the bottomsurface 18 b of the high frequency transformer core 18.

In other embodiments (not all explicitly shown), the height H_(D) of thedifferential transformer core 16 may be greater than the height H_(N) ofthe GN transformer core 14, greater than the height H_(R) of the highfrequency transformer core 18 and/or greater than the combined totalheight of H_(N) and H_(R). As such, the differential transformer core 16may extend partially or entirely through one or both the GN transformercore 14 and the high frequency transformer core 18. For example, withreference to FIG. 4, the differential transformer core 16 may extendabove the top surface 14 a of the GN transformer core 14 and below thebottom surface 14 b of GN transformer core 14, wherein the differentialtransformer core 16 only extends partially through the high frequencytransformer core 18 without protruding from the bottom surface 18 bthereof. In other embodiments, the height H_(D) of the differentialtransformer core 16 may be greater than the combined heights H_(N) andH_(R) of the GN transformer core 14 and the high frequency transformercore 18 so that the differential transformer core 16 extends above thetop surface 14 a of GN transformer core 14 and below the bottom surface18 b of high frequency transformer core 18. Alternately, a top surface16 a of the differential transformer core 16 may be disposed within theinner chamber 17 a of the GN transformer core 14 without protrudingtherefrom, and a bottom surface 16 b of the differential transformercore 16 may be disposed within the inner chamber 17 b of the highfrequency transformer core 18 without protruding therefrom, as shown inFIG. 7.

The three core assembly 12 may include a metal magnetic shield 30disposed below the differential transformer core 16 (i.e., differentialtransformer core 16 is disposed on top of metal magnetic shield 30). Insome embodiments, shield 30 may be placed in alterative positionsrelative to differential transformer core 16, such as, for example, ontop of top surface 16 a of differential transformer core 16, between thetop and bottom surfaces 16 a, 16 b of differential transformer core 16,within a central cavity 16c of differential transformer core 16, and/ordisposed about the differential transformer core 16. It is contemplatedthat shield 30 may be fabricated from alternative, non-metallicmaterials, such as, for example, a dielectric material such that shield30 may act solely as a spacer or shim. When shield 30 is used as aspacer or shim, shield 30 may raise or lower differential transformercore 16 to the appropriate position within central cavity/volume 17 ofthe stacked GN transformer core 14 and the high frequency transformercore 18.

In order to minimize the space occupied by the three core assembly 12,the dimensions of the cores of the GN transformer core 14, differentialtransformer core 16, and high frequency transformer core 18 may bedifferent than the corresponding cores found in conventional AFCIs andGFCIs. In the AFCI/GFCI 10, the height of the GN transformer core 14 isreduced compared to the corresponding GN transformer core in aconventional GFCI. The cross-sectional area of the high frequency core18 is also different compared to a corresponding high frequency core ina conventional AFCI. Specifically, the height HR of the high frequencycore 18 is reduced, the outer diameter 28 is increased and the innerdiameter 26 is reduced when compared to a high frequency core in aconventional AFCI. The cross-sections of each of the transformer cores14, 16, and 18 are substantially rectangular in shape.

With reference to FIG. 9, the differential transformer core 16 is nestedwithin the GN transformer core 14 and the high frequency transformercore 18 so that core 16 more closely surrounds conductors 32 passingthere-through. The differential transformer core 16 is designed to havea greater degree of sensitivity and precision than the high frequencytransformer core 18 and the GN transformer core 14. The differentialtransformer core 16 is more sensitive, in part, because it needs todetect a difference in current in the milliamp range on a circuit thatoperates in the 15 Amp range. As such, it is preferable to position themore sensitive and precise differential transformer core 16 within theGN transformer core 14 and the high frequency transformer core 18 sothat the core 16 can be symmetrical with respect to the conductors 32passing therethrough and in closer proximity to said conductors 32. Thiscan minimize load shift which can occur due to the positioning of eachof the conductors 32 with respect to the core 16. Such positioning ofconductors 32 affects the magnetic flux and the output on the secondarywindings. For example, improperly positioned conductors 32 may result inan inaccurate signal being generated by the secondary windings. Thethree core assembly 12, which includes the GN transformer core 14,differential transformer core 16, and high frequency transformer core18, is positioned on one side of the PC Board, whereas the fourthtransformer core 22 (FIG. 1B) and the current sensor are positioned onthe other side of the PC Board. Both phase and neutral conductors passthrough the cores of the three core assembly 12 but only the phaseconductor passes through the current sensor. As such, the current pathsof the phase and neutral conductors are different in their physicalrouting which can lead to external field effects on the differentialtransformer core 16. In order to minimize this, as described above, ametal magnetic shield 30 is disposed below the differential transformercore 16.

With respect to electrical performance, when the three cores 14, 16, and18 are arranged in this manner (i.e., the GN transformer core 14 and thehigh frequency transformer core 18 are in the stacked configuration andthe differential transformer core 16 is disposed concentrically withinthe stacked GN transformer core 14 and the high frequency transformercore 18), it is important to tune the cores in order to ensure properoperation. In general, an arc fault creates noise in a wide band offrequencies. This noise is small compared to the total power linefrequency current and as such, requires amplification in order to bedetected. However, building an amp that has a wide bandwidth can bedifficult. In addition because of interwinding capacitance of the highfrequency transformer core 18, at high frequencies, the high frequencytransformer core 18 has very narrow bandwidths. This is due to the factthat at high frequency, the inductive and capacitive components of thesignal on the secondary windings affect the resonant frequency of thehigh frequency transformer core 18. Further, an amp with a widerbandwidth may come at the cost of amplifier efficiency or cost ifmultiple amplifier stages are required for different portions of thespectrum. As such, it is desirable to limit the frequency response ofthe amp while still identifying problematic wide band noise indicativeof arcing and align it with the resonance frequency of the highfrequency transformer core 18. One approach to do this is via empiricalexperimentation. For example, characteristics of the three cores 14, 16,and 18 can be altered and the output measured in response to a knownwideband input signal indicative of arcing. This could be done eitherdirectly at the output of a core or at the output of further downstreamcomponents such as an amp fed by a core.

Characteristics of the core that can be altered include physicaldimensions/shape or electrical design. For example, if the core is inthe form of a toroid, its radius and cross-sectional dimension/heightcan be varied and experimented with such that a relationship can beestablished between the physical properties and the frequency response.Alternatively, one can vary the number of turns of a secondary windingand determine the corresponding frequency response. In the presentembodiment, the high frequency transformer core 18 has secondarywindings that surround only a portion of the core. For example, in oneembodiment, the secondary windings surround about ¼ of the core. Inother words, if the core is a full 360 degree surface of revolutionabout an axis, the secondary windings surround the core through 90degrees of the 360 degrees of revolution. This is due to the fact thatonly a certain number of secondary windings are required in the presentapplication and it is easier, from a manufacturing standpoint, to placethe secondary windings directly next to each other on the core than tocontrol the spacing between the secondary windings.

In addition to varying the characteristics of the core, various circuitcomponents may be altered to optimize the design. For example, a groundneutral signal can be tuned by varying the RC circuit R37 & C26 (see box34 in FIG. 1B). In addition, if the GN transformer core 14 is madephysically smaller, corresponding circuitry may have a larger gain tocompensate for this. Additionally, components R17, R18, and C12 ofamplifier circuit 36 (FIG. 1C) can be altered to optimize the highfrequency signal amplification.

In some embodiments, GN transformer core 14 may include an iron alloy,differential transformer core 16 may include an iron wafer assembly, andhigh frequency transformer core 18 may include a dielectric material.

While certain embodiments of the disclosure have been described herein,it is not intended that the disclosure be limited thereto, as it isintended that the disclosure be as broad in scope as the art will allowand that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision additional modifications, features, and advantages withinthe scope and spirit of the claims appended hereto.

We claim:
 1. A circuit interrupting device comprising: a current sensorcore; a core assembly defining a longitudinal axis and including: agrounded neutral transformer core; a high frequency transformer core,the grounded neutral transformer core and the high frequency transformercore are stacked along the longitudinal axis; and a differentialtransformer core disposed within a cavity defined by both the groundedneutral transformer core and the high frequency transformer core.
 2. Thecircuit interrupting device of claim 1, wherein the high frequencytransformer core is a non-ferrous core.
 3. The circuit interruptingdevice of claim 1, further comprising a printed circuit board, whereinthe core assembly is located on one side of the printed circuit boardand the current sensor core is located on the other side of the printedcircuit board.
 4. The circuit interrupting device of claim 1, whereinthe differential transformer core extends along at least a portion of aheight of the grounded neutral transformer core and at least a portionof a height of the high frequency transformer core, the height of eachof the grounded neutral transformer core and the high frequencytransformer core being defined along the longitudinal axis.
 5. Thecircuit interrupting device of claim 1, wherein at least one of thecores of the core assembly has a cross-section having a perimeter,wherein the perimeter has one or more portions selected from the groupconsisting of a straight portion and an arcuate portion.
 6. The circuitinterrupting device of claim 1, further comprising a non-ferrous spacerbeing configured to position the differential transformer core withinthe core assembly.
 7. The circuit interrupting device of claim 1,further comprising a magnetic shield disposed below the differentialtransformer core.
 8. The circuit interrupting device of claim 1, furthercomprising a magnetic shield disposed above the differential transformercore.
 9. The circuit interrupting device of claim 1, further comprisinga magnetic shield, wherein the differential transformer core defines adifferential core cavity and the magnetic shield is disposed at leastpartially within the differential core cavity.
 10. The circuitinterrupting device of claim 1, further comprising a magnetic shield atleast partially surrounding the differential transformer core.
 11. Thecircuit interrupting device of claim 1, wherein the differentialtransformer core is configured to receive a plurality of conductivepaths therethrough.
 12. The circuit interrupting device of claim 11,wherein the differential transformer core is arranged symmetricallyabout the plurality of conductive paths.
 13. A method of manufacturing acircuit interrupting device, comprising: arranging a plurality of coresinto a core assembly, the plurality of cores including a groundedneutral transformer core, a high frequency transformer core, and adifferential transformer core, each of the plurality of cores configuredto selectively output a signal, wherein the step of arranging furtherincludes: stacking the grounded neutral transformer core and the highfrequency transformer core along a longitudinal axis defined by the coreassembly; and disposing the differential transformer core at leastpartially within a cavity defined by both the grounded neutraltransformer core and the high frequency transformer core.
 14. The methodof claim 13, further comprising: extending a conductive path through thecavity; applying a fault signal indicative of an electrical fault on theconductive path; selecting at least one of the plurality of cores andmeasuring a frequency response of the output signal of the selectedcore; tuning the selected core such that the frequency response isvaried; and measuring the frequency response.
 15. The method of claim 14wherein the step of tuning includes varying at least one characteristicof the selected core, the characteristic selected from the groupconsisting of: a height; an inside diameter; an outside diameter; across-sectional shape; a cross-sectional area; a number of windingturns; a winding wire gauge; and a spacing of the winding turns.
 16. Themethod of claim 14 wherein the frequency response of the output signalof the selected core is narrowed.
 17. The method of claim 16 wherein thefault signal includes one or more of a ground fault and an arc fault.18. The method of claim 17, wherein the frequency response of the outputsignal of the selected core is aligned with respect to wide band noiseindicative of the fault signal.
 19. The method of claim 14, furthercomprising: receiving the output signal of the selected core at an inputof a signal processor circuit; the signal processor circuit generating aprocessed signal output; wherein the step of tuning further includesvarying the processing done by the signal processor circuit.
 20. Themethod of claim 19, wherein the signal processor circuit furtherincludes an amplifier having a gain and the step of varying theprocessing done by the signal processor circuit further includes varyingthe gain of the amplifier.
 21. The method of claim 19, wherein thesignal processor circuit further includes a resistor-capacitor (RC)network, wherein the step of varying the processing done by the signalprocessor circuit further includes varying the value of one or more of aresistor and a capacitor of the RC network.
 22. The method of claim 19,wherein the signal processor circuit further includes a processor,wherein the step of varying the processing done by the signal processorcircuit further includes varying a programming of the processor.